Magnetic recording in its conventional form suffers from super-paramagnetic instabilities at high bit densities. As the grain size of the magnetic recording medium is decreased in order to increase areal density, a threshold known as super-paramagnetic limit at which stable data storage is no longer feasible is reached. This threshold is dependent not only on the magnetic recording medium material, but also for a given temperature. One of the solutions to overcome this threshold is to use magnetic medium material with very high magnetic anisotropy. The medium is then softened temperately by heating during writing to temperatures at which an external write field can reverse the magnetization. This concept is known as heat-assisted magnetic recording (HAMR).
HAMR systems require spatial and temporal variations of the heat profile to be managed. In particular, lateral heat diffusion in HAMR media is an important requirement for confining the heated region in the media to desired dimensions. Typical HAMR systems utilize a heat producing means external to the magnetic recording medium. For example, many solutions involve activating a laser mounted on or near the recording head and focused on the magnetic recording medium. The laser is then activated to heat up a heating spot in the magnetic recording medium near and facing the recording head. However, heating efficiency and the heating spot size are key challenges in traditional HAMR systems which require a lot of energy for the laser light during HAMR-system writing. Much of the laser's energy is lost in the laser source to waveguide coupling, the laser light transmission through the near field transducer (NFT), and the light coupling through the gap between the head and the magnetic recording medium. In addition, the heating spot size of the laser on the recording medium must be much smaller than the diffraction limit. Due to these deficiencies in present HAMR systems, currently, a fully optimized near field optical system only conveys 1-2% of the laser energy into the magnetic recording medium.
Thus, what is needed is a data storage device with a magnetic recording medium having controlled heat transfer characteristics that is both suitable to perform heat-assisted magnetic recording and utilizes a larger percentage of the energy generated for heating the magnetic recording medium within a small heating spot size. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.